Fire alarm



SePt- 29, 1959 J. c. HOLLINGSWORTH FIRE ALARM Filed April 27, 1955 JessC .Hollzngsworh www@ United States Patent O FIRE ALARM Jess C.Hollingsworth, Rockford, Ill.

Application April 27, 195'5, Serial No. 504,152

1 Claim. (Cl. 340-232) 'Ihis invention relates to a new and improvedlire alarm.

The principal object of my invention is to provide a tire alarm ofsimple, practical and economical design, and one that is so constructedthat it is certain to operate instantly inV the event of tire in theparticular room or hallway or other area in a building in which thealarm is installed for re protection.

A salient feature of the present invention is the employment of aflexible string or cord extending all around a room or all around ahallway or other area in a building, the string or cord being carried onsuitable guides on the walls and maintained under tension by a springthat is stretched between the adjoining ends thereof at the alarm box,where a pair of contact arms also connected with the opposite ends ofthe spring are held by the string out of engagement with fixed contactsonly so long as the string remains intact, the spring serving to drawthe arms together and close the contacts instantly when the string burnsand breaks, whereby to sound the alarm.

Another feature is the provision on the alarm box of a hinged door thathas spring means tending to throw it open, the door being releasablylatched in closed position by engagement of catches with keepers on theaforementioned contact arms, so that the door will be automaticallyreleased at the same time that the alarm is sounded, the contact arms atthat time being drawn toward each other by the tension spring and beingthereby also disconnected from the spring-pressed door so that the doorswings open.

The invention is illustrated inthe accompanying drawing, in which- Fig.l is a front view of the fire alarm box showing the cover in closedposition but broken away to disclose the alarm mechanism inside the boxand the improvements added in accordance with my invention;

Fig. 2 is a section on the line 2 2 of Fig. l;

Figs. 3 and 4 are sectional details on lines 3-3 and 4-4 of Fig. 1, and

Fig. 5 is a plan view of a typical installation of my improved lirealarm.

The same reference numerals are applied to corresponding partsthroughout the views.

Referring first to Fig. 2, the alarm bell 6 and striker 7 are similar towhat are disclosed in Edwards Patent No. 2,041,995, the bell beingmounted in any suitable way upon a hollow casing 8 which is to a largeextent received within the hollow of the bell itself for compactness ofconstruction. Within the casing 8 is mounted the striker mechanismconsisting of a solenoid 9 for which the striker 7 serves as an armatureso that when the winding of the solenoid is energized from a suitablecircuit the striker 7 is reciprocated rapidly and sounds the bell. Thewinding of the solenoid 9 has terminal conductors 10 and 11 which extendfrom the casing 8, conductor 10 extending out of the alarm box 12 inwhich lCC the alarm bell is housed, as appears in Fig. l, and conductor11 extending only to one side of the switch 13, another conductor 14extending from the other side of the switch out of the alarm box.Conductors 10 and 14 may be connected in any suitable way with a sourceof electric current supply.

Switch 13 comprises two spaced parallel metallic bars 15- and 16 mountedin insulated relationship to one another by means of insulators 17 onthe same panel 18 onto which the bell supporting casing 8 is fastened,as by screws 19. The lower bar 16 has a pair of arms 20 and 21 pivotedon its opposite ends, as indicated at 22, and these arms haveprojections 23 on their pivoted end portions serving as contactsarranged to engage other contact projections 24 provided on the adjacentends of the upper bar 1S. A coiled tension spring 25 is stretchedbetween the free upper ends of the arms 20-21 and tends normally toclose the contacts just mentioned, so as to sound the alarm bell 6, andthat is what occurs when the string or cord 26 burns and breaks.

The string or cord 26 is attached at its one end to the upper end of arm20 and extends through an opening 27 in one side wall of the box 12 andis strung along the walls completely around the entire room, hallway, orother area in the building and back to the other side of the box 12,where it extends through another opening 28 and is attached to the upperend of the arm 21. Suitable guides, such as eyelets 29, may be providedat spaced intervals and especially at the corners of the room for lowfriction support of the string, and, of course, the string must be drawnup reasonably taut before it is attached to the second arm 21, and thespring 25 must also be stretched enough to maintain the string undertension. The panel 18 previously mentioned is suitably secured to theback wall of box 12, as indicated at 30, and the back wall has holes 31therein through which screws or bolts may be entered to fasten the boxto the wall of the room, wherever the alarm is being installed.Projections 32 on the inside of the side Walls of the box limit theoutward movement of the arms 20 and 21 and serve to insure properregistration of keeper projections 33 on the arms with spring catchprojections 34 provided on the inner side of a door 35 hinged as at 36to the bottom wall of the box and serving to close the box and concealthe alarm bell 6 and automatic switch 13. One or two grasshopper typetorsion springs 37 are provided tending to throw the door open, each ofthese having its coiled portion mounted on a screw 38 entered in theside wall of the box, as shown, while the arm 39 on one end of thespring bears against the bottom of the box and the arm 40 provided bythe other end of the spring bears against the inner side of the door.Hence, when the string 26 burns and breaks, not only is the alarm bellsounded by virtue of the arms 20-21 closing contacts under action ofspring 2S, but the door 35 is also thrown open by springs 37 at the sametime when the arms 20-21 are drawn toward one another and away from thecatches 34.

In operation, the string or cord 26 is located usually adjacent thepicture molding so it will not show and so that there is nothing tointerfere with extending it over one or more doorways. The alarm box 12is preferably located over a doorway so that the bell will be heard morereadily in other parts of the building when the alarm is sounded. Thestring 26 is selected for its quick charring and burning and may also beimpregnated to hasten combustion so that a re will not get started toowell before the heat causes the string to burn and break, sounding thealarm. The automatic opening of the door 35 is advantageous because themechanism in the box is thereby concealed and protected up to the timethe alarm is operated, and, when that occurs, the open door allows thealarm bell to be heard more readily.

While I have shown a single string extending from its connection withone arml all around' the room and back to the box for connection withthe other arm it should be clear that two strings can be used, eachstring holding the one arm to which it is attached in retracted positionagainst the pull of the spring 25- and being anchored at its far end inany suitable Way, as for example, to one of the eyelets 29. In thatevent, the burning and breaking Yof either string would still result inthe sounding of the alarm .because the arm 20 or 21 connected with thatstring would be released to close the contacts 23 and 24, even thoughthe other armwas not released.

It is believed the foregoing description conveys a good understanding ofthe objects land advantages of my invention. The appended claim has'been drawn to cover all legitimate modifications and adaptations.

claim:

A re alarm device of the character described comprising an open fronthousing havin-g a vertical back Wall, spaced vertical side walls and ahorizontal bottom wall, an Aalarm bell unit mounted in said housing onthe back wall and including electromagnetic means for actuation of areciprocable striker for sounding the Vbell when the circuit iscompleted through said electromagnetic means, spaced parallel conductorbarsmounted in electrically insulated relation to said housing'on theback wall thereof in transverse relationship to the bottom portion ofsaid housing, arms pivotally mountcdon the opposite ends of one of saidbars and extending up- 4 wardly in the opposite side portions of saidhousing on opposite sides of the `alarm bell unit, a tension springinterconnecting the upper ends of said arms tending normally to move thesame inwardly toward one another into contact with the opposite ends ofthe other of said bars so as to complete the electrical circuit throughsaid electromagnetic means and sound the bell, strings of readilycombustible material attached to the upper ends of said arms andextending freely from opposite sides of the housing into a room or thelike to be protected from tire, said strings being suitably securedholding the arms in retracted position against the action of said springand being thereby also maintained under tension, a door verticallydisposed closing the open front of said housing and hinged to the bottomwall thereof, spring means urging said door normally toward openedposition, and interengaging catch means on the opposite side portions ofsaid door and said arms holding the door releasably in closed positionuntil the arms swing inwardly under action of theirtension spring torelease saiddoor.

References Cited in the le of this patent'V UNrTED STATES yPrrrnisrs

